Conventional fibers are useful in a variety of applications including reinforcements, textiles, and acoustical and thermal insulation materials. Although mineral fibers (e.g., glass fibers) are typically used in insulation products and non-woven mats, depending on the particular application, organic fibers such as polypropylene, polyester, and multi-component fibers may be used alone or in combination with mineral fibers in forming the insulation product or non-woven mat.
Fibrous insulation is typically manufactured by fiberizing a molten composition of polymer, glass, or other mineral and spinning fine fibers from a fiberizing apparatus, such as a rotating spinner. To form an insulation product, fibers produced by the rotating spinner are drawn downwardly from the spinner towards a conveyor by a blower. As the fibers move downward, a binder material is sprayed onto the fibers and the fibers are collected into a high loft, continuous blanket on the conveyor. The binder material gives the insulation product resiliency for recovery after packaging and provides stiffness and handleability so that the insulation product can be handled and applied as needed in the insulation cavities of buildings. The binder composition also provides protection to the fibers from interfilament abrasion and promotes compatibility between the individual fibers.
In addition, previous workers have focused on the use of polyacrylic acid with a polyhydroxy crosslinking agent or carbohydrate-based chemistry that is linked to the Maillard reaction. See, e.g. U.S. Pat. No. 7,772,347 to Swift, et al. Polyacrylic acid binders, however, have several drawbacks. For example, polyacrylic acid binders use petroleum based materials and costs typically at least two times that of current phenolic binder systems. In addition, the high viscosity and different cure characteristics pose process difficulties. Also, Maillard reaction-based products have an undesirable dark brown color after curing. Further, the use of large amounts of ammonia needed to make the binder presents a safety risk and possible emission problems.
Hawkins, et al. in U.S. patent publication 2011/0021101, published Jan. 27, 2011 teach a formaldehyde-free binder comprising modified starches (which contain multiple hydroxyl groups) crosslinked with various reagents, including polycarboxylic acids (and their anhydrides and salts) such as citric, adipic, polyacrylic, and others. Generally this reaction is catalyzed by a phosphorous-containing catalyst or cure accelerator, such as sodium hypophosphite. However, Hawkins et al, fail to teach any phosphorus-containing compound as a crosslinking agent. A similar disclosure is found in Arkens, et al. U.S. Pat. No. 5,661,213, Arkens, et al, U.S. Pat. No. 6,221,973 and Taylor, et al. U.S. Pat. No. 6,331,350, but these also fail to teach any phosphorus-containing compound as a crosslinking agent.
In addition, phosphorus compounds are known as a flame or fire retardant and have been used in fibrous insulation products as such. U.S. Pat. No. 5,284,700 to Strauss, et al, and U.S. patent publication 2006/0178064 to Balthes, et al, are examples.
Finally, it is also known to use acids, including phosphoric acid, as a pH adjuster in various product binders, as is taught in U.S. Pat. No. 3,944,690 to Distler, et al., and U.S. Pat. No. 3,669,638 to Wong, et al.
In view of the existing problems with current binders, there remains a need in the art for a binder system that is not petroleum dependent, has no added formaldehyde, is bio-based and environmentally friendly, and is cost competitive.